Working memory costs of task switching

Although many accounts of task switching emphasize the importance of working memory as a substantial source of the switch cost, there is a lack of evidence demonstrating that task switching actually places additional demands on working memory. The present study addressed this issue by implementing task switching in continuous complex span tasks with strictly controlled time parameters. A series of 4 experiments demonstrate that recall performance decreased as a function of the number of task switches and that the concurrent load of item maintenance had no influence on task switching. These results indicate that task switching induces a cost on working memory functioning. Implications for theories of task switching, working memory, and resource sharing are addressed.     

Learning correct responses and errors in the Hebb repetition effect: two faces of the same coin

In a serial recall task, the Hebb repetition effect occurs when recall performance improves for a sequence repeated throughout the experimental session. This phenomenon has been replicated many times. Nevertheless, such cumulative learning seldom leads to perfect recall of the whole sequence, and errors persist. Here the authors report evidence that there is another side to the Hebb repetition effect that involves learning errors produced in a repeated sequence. A learning measure based on past recalls (correct or incorrect) shows that the probability of a given response increases with the number of prior occurrences of that response. The pattern of results reveals another manifestation of the Hebb repetition effect and speaks to the nature of implicit learning.     

Time-related decay or interference-based forgetting in working memory?

The time-based resource-sharing model of working memory assumes that memory traces suffer from a time-related decay when attention is occupied by concurrent activities. Using complex continuous span tasks in which temporal parameters are carefully controlled, P. Barrouillet, S. Bernardin, S. Portrat, E. Vergauwe, & V. Camos (2007) recently provided evidence that any increase in time of the processing component of these tasks results in lower recall performance. However, K. Oberauer and R. Kliegl (2006) pointed out that, in this paradigm, increased processing times are accompanied by a corollary decrease of the remaining time during which attention is available to refresh memory traces. As a consequence, the main determinant of recall performance in complex span tasks would not be the duration of attentional capture inducing time-related decay, as Barrouillet et al. (2007) claimed, but the time available to repair memory traces, and thus would be compatible with an interference account of forgetting. The authors demonstrate here that even when the time available to refresh memory traces is kept constant, increasing the processing time still results in poorer recall, confirming that time-related decay is the source of forgetting within working memory.     

The effect of spatial frequency content on parameters of eye movements

Two experiments were conducted to examine the influence of the spatial frequency content of natural images on saccadic size and fixation duration. In the first experiment 10 pictures of natural textures were low-pass filtered (0.04-0.76 cycles/deg) and high-pass filtered (1.91-19.56 cycles/deg) and presented with the unfiltered originals in random order, each for 10 s, to 18 participants, with the instruction to inspect them in order to find a suitable name. The participants' eye movements were recorded. It was found that low-pass filtered images resulted in larger saccadic amplitudes compared with high-pass filtered images. A second experiment was conducted with natural stimuli selected for different power spectra which supported the results outlined above. In general, low-spatial frequencies elicit larger saccades associated with shorter fixation durations whereas high-spatial frequencies elicit smaller saccades with longer fixation durations.     

Do working-memory executive components mediate the effects of age on strategy selection or on strategy execution? Insights from arithmetic problem solving

Younger and older adults performed an inequality verification task (7+6 < 15, Yes/No?) in a control condition and in a dual-task condition where they simultaneously performed an executive-component task. Arithmetic-problem characteristics were manipulated in order to test strategy selection (i.e., choice of appropriate strategies in order to improve performance) and strategy execution (i.e., performance of the cognitive processes involved in each strategy). Results revealed that strategy selection changes with age: Older adults mainly selected one type of strategies in contrast to younger adults who used several types of strategies. These age-related changes were similar in the control and dual-task conditions. Strategy execution also changed with age, as shown by larger age-related differences on hardest problems. These age-related changes were larger in the dual-task condition, compared to the control condition. This impact of executive components as mediator of age-related changes depended on general age-related slowing. We discuss these findings in order to further understand the effects of age on arithmetic performance.     

Cognitive and linguistic skills in Swedish children with cochlear implants - measures of accuracy and latency as indicators of development

The purpose of the present study was to examine working memory (WM) capacity, lexical access and phonological skills in 19 children with cochlear implants (CI) (5;7-13;4 years of age) attending grades 0-2, 4, 5 and 6 and to compare their performance with 56 children with normal hearing. Their performance was also studied in relation to demographic factors. The findings indicate that children with CI had visuospatial WM capacities equivalent to the comparison group. They had lower performance levels on most of the other cognitive tests. Significant differences between the groups were not found in all grades and a number of children with CI performed within 1 SD of the mean of their respective grade-matched comparison group on most of the cognitive measures. The differences between the groups were particularly prominent in tasks of phonological WM. The results are discussed with respect to the effects of cochlear implants on cognitive development.     

What is the impact of the explicit knowledge of sequence regularities on both deterministic and probabilistic serial reaction time task performance?

The aim of this study was to explore the role of prior explicit sequence knowledge by comparing its influence on serial reaction time (SRT) performance with either a deterministic or a probabilistic sequence. The results confirm that, with a deterministic sequence, preliminary explicit learning improves SRT performance. On the other hand, with a probabilistic sequence, the results show no advantage for SRT performance in explicit-learning conditions. In addition, by using the process dissociation procedure (Jacoby, 1991), we show that performance on a subsequent generation task was more sustained by controlled processes for participants in the explicit-learning conditions than for those in the incidental condition. On the whole, these results, showing that the influence of explicit knowledge can be suppressed in certain specific conditions, are consistent with the intervention of both implicit and explicit mechanisms in SRT tasks, and the results also show that their relative influence can be modulated by the particular demands of the task.     

Beyond the Class Norm: Bullying Behavior of Popular Adolescents and its Relation to Peer Acceptance and Rejection

This study examined to what extent bullying behavior of popular adolescents is responsible for whether bullying is more or less likely to be accepted or rejected by peers (popularity-norm effect) rather than the behavior of all peers (class norm). Specifically, the mean level of bullying by the whole class (class norm) was split into behavior of popular adolescents (popularity-norm) and behavior of non-popular adolescents (non-popularity-norm), and examined in its interaction with individual bullying on peer acceptance and peer rejection. The data stem from a peer-nominations subsample of TRAILS, a large population-based sample of adolescent boys and girls (N = 3312). The findings of multilevel regression analyses demonstrated that the negative impact of individual bullying on peer acceptance and the positive impact on peer rejection were particularly weakened by bullying by popular adolescents. These results place the class-norm effects found in previous person-group dissimilarity studies in a different light, suggesting that particularly bullying by popular adolescents is related to the social status attached to bullying.

The Development of Hyperactive–Impulsive Behaviors During the Preschool Years: The Predictive Validity of Parental Assessments

The objectives of this study were to establish the different developmental trajectories of hyperactive-impulsive behaviors on the basis of both mother and father ratings at 19, 32, 50, and 63 months, and to examine the predictive validity of these trajectories with respect to later hyperactive-impulsive behaviors, as rated by teachers in the first 2 years of school. Hyperactive-impulsive behaviors were assessed in a population-based sample of 1,112 twins (565 boys and 547 girls) at 19, 32, 50, and 63 months of age. The results revealed a differentiated and consistent view of developmental trajectories of hyperactive-impulsive behaviors derived from these repeated assessments, with 7.1% of children seen by mothers (7% for fathers) as displaying high and stable hyperactive-impulsive behaviors. According to mother ratings, children on a high-chronic trajectory were more likely than other children to display hyperactive-impulsive behaviors at 72 and 84 months according to their teachers. Repeated measures over time and father-based trajectories significantly added to the prediction teacher later ratings of hyperactive-impulsive behaviors. These results support the predictive validity of parental assessment of hyperactive-impulsive behaviors during the preschool years and their use to identify children at risk for further evaluation and possible intervention.     

Investment in body image for self-definition results in greater vulnerability to the thin media than does investment in appearance management

This study investigated the effect of thin images according to two dimensions of body-image (BI) investment. Ninety-five females were classified as high or low investors based on the Appearance Schemas Inventory-Revised Self-Evaluative Salience (SES) and Motivational Salience (MS) subscales. Participants viewed advertisements portraying either the thin ideal or products. Results indicated that both women high in SES and MS reported lowered appearance self-esteem but greater BI importance following thin exposures. However, only the high SES group reported greater BI dissatisfaction and importance of current-ideal discrepancies after seeing thin images. Although highly invested women (regardless of their motivation for investment) are more responsive to thin media images than are women low in investment, those invested for self-definition are affected on more dimensions than are those invested for appearance management.